Cardwellia sublimis, a giant of the Proteaceae family, was one of the ‘big things’ we encountered during our visit to the Paluma rainforest late last year. Its local name, Northern Silky Oak, harks back to colonial times when its timber with oak-like grain was highly valued for building Queenslander-style houses and furniture
Cardwellia sublimis is endemic to well developed rain forest areas in north eastern Queensland. Some tall specimens may be spotted near the road to Paluma (photo above). Even taller emergent trees almost 40 m high have been reported to occur in optimal conditions.
Cardwellia sublimis has large compound leaves with the leaflets glossy on the upper side and having a golden-brown sheen underneath (photo above).
Cardwellia sublimis produces beautiful panicles of cream flowers (first photo on this page) that are followed by very large brown woody fruits (lower centre of photo above). These fruits remain for quite a while on the tree where they split open to release winged seeds whose dispersal is probably assisted by wind.
Within the rainforest, Cardwellia sublimis tends to blend in amongst other trees and its lofty crown may be hard to spot. Fortunately its large fallen seed cases (photo above) persist for a long time on the ground and provide a helpful clue that Cardwellia sublimis is probably growing nearby.
The seedlings of Cardwellia sublimis have distinctive cotyledons reminiscent of bright green butterfly wings (photo above). Although the seeds are reported to germinate readily in 14 to 24 days, attempts to grow Cardwellia sublimis in plantations have not been successful.